ALUA parameters in the output of ESX/ESXi 4.x and ESXi 5.x commands
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ALUA parameters in the output of ESX/ESXi 4.x and ESXi 5.x commands

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Article ID: 310442

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Updated On:

Products

VMware vSphere ESXi

Issue/Introduction

When the storage array of an ESX/ESXi 4.1 or ESXi 5.x host supports Asymmetric Logical Unit Access (ALUA), the output of storage commands has some new parameters. This article provides information about these new parameters.


Environment

VMware ESXi 4.1.x Installable
VMware ESX 4.1.x
VMware vSphere ESXi 5.1
VMware vSphere ESXi 5.0
VMware ESXi 4.1.x Embedded

Resolution

About ALUA

ALUA devices can operate in two modes: implicit and/or explicit.
Explicit ALUA devices allow the host to use the Set Target Port Group task management command to set the Target Port Group's state. In implicit ALUA, a device's Target Port Group states are managed by the target device itself.

New parameters

If you run the command:
In ESX/ESXi 4.x – #esxcli nmp device list -d naa.60060160455025000aa724285e1ddf11,
In ESX/ESXi 5.x #esxcli storage nmp device list -d naa.60060160455025000aa724285e1ddf11
You see output similar to:
naa.60060160455025000aa724285e1ddf11
Device Display Name: DGC Fibre Channel Disk (naa.60060160455025000aa724285e1ddf11)
Storage Array Type: VMW_SATP_ALUA_CX
Storage Array Type Device Config: {navireg=on, ipfilter=on}{implicit_support=on;explicit_support=on; explicit_allow=on;alua_followover=on;{TPG_id=1,TPG_state=AO}{TPG_id=2,TPG_state=ANO}}
Path Selection Policy: VMW_PSP_FIXED_AP
Path Selection Policy Device Config: {preferred=vmhba1:C0:T0:L0;current=vmhba1:C0:T0:L0}
Working Paths: vmhba1:C0:T0:L0

The output may contain these new device configuration parameters:

  • implicit_support=on

    This parameter shows whether or not the device supports implicit ALUA. You cannot set this option as it is a property of the LUN.
  • explicit_support

    This parameter shows whether or not the device supports explicit ALUA. You cannot set this option as it is a property of the LUN.
  • explicit_allow

    This parameter shows whether or not the user allows the SATP to exercise its explicit ALUA capability if the need arises during path failure. This only matters if the device actually supports explicit ALUA (that is, explicit_support is on). This option is turned on using the esxcli command enable_explicit_alua and turned off using the esxcli command disable_explicit_alua.

  • alua_followover

    This parameter shows whether or not the user allows the SATP to exercise the follow-over policy, which prevents path thrashing in multi-host setups. This option is turned on using the esxcli command enable_alua_followover and turned off using the esxcli command disable_alua_followover.
If you run the command:
In ESX/ESXi 4.x – #esxcli nmp path list -d naa.60060160455025000aa724285e1ddf11
In ESXi 5.x fc.20000000c987f8c5:10000000c987f8c5-fc.50060160bce0383c:5006016e3ce0383c-naa.60060160455025000aa724285e1ddf11
Runtime Name: vmhba2:C0:T1:L0
Device: naa.60060160455025000aa724285e1ddf11
Device Display Name: DGC Fibre Channel Disk (naa.60060160455025000aa724285e1ddf11)
Group State: active unoptimized
Array Priority: 0
Storage Array Type Path Config: {TPG_id=2,TPG_state=ANO,RTP_id=18,RTP_health=UP}
Path Selection Policy Path Config: {current: no; preferred: no}

fc.20000000c987f8c5:10000000c987f8c5-fc.50060160bce0383c:500601663ce0383c-naa.60060160455025000aa724285e1ddf11
Runtime Name: vmhba2:C0:T0:L0
Device: naa.60060160455025000aa724285e1ddf11
Device Display Name: DGC Fibre Channel Disk (naa.60060160455025000aa724285e1ddf11)
Group State: active
Array Priority: 1
Storage Array Type Path Config: {TPG_id=1,TPG_state=AO,RTP_id=7,RTP_health=UP}
Path Selection Policy Path Config: {current: no; preferred
: no}

In the output, TPG_state = ANO means Active/Non-Optimized and TPG_state = AO means Active/Optimized.
Notes:
  • Target Port Groups (TPG) allow path grouping and dynamic load balancing. Each port in the same TPG has the same port state, which can be one of these:
    • Active/Optimized
    • Active/Non-Optimized
    • Standby
    • Unavailable
    • In-transition

  • Active indicates that the LUN is active on a TPG. If the LUN is not active, a failover would have to be requested to the storage processor to make it active.
  • Optimized has the best performance. This is reported by the storage processor as per its current internal organization of paths/cache.


Additional Information

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